Current automatic signature machines have the writing pantographs suspended above the surface of the document to be written on. Because the pantographs are designed to write in a coordinate X-Y plane over a limited area, such pantographs must write on perfectly flat surfaces. Therefore, for an automatic machine of this type, the documents must be singly moved on to and off of a flat surface located below the pantographs. However, it is necessary to make certain that the document does not interfere with the support mechanism of the pantographs system. This has been accomplished by cantilevering the pantograph far enough away so that any desired size document can freely be positioned under the pantograph and so that writing can be applied to any portion of the document.
It should also be appreciated that each document in a stack of documents to be written on will have a common fixed writing area. However, the particular area to be written on for any document may be located at any position on the document, and vary both laterally and longitudinally from one set of documents to the next. It therefore becomes necessary to make it possible to adjust both the X and Y position of the document before it can be written on. Any automatic transport mechanism for documents must also be certain not to skew the document in any manner as the document is delivered to the writing surface.
One prior art delivery mechanism for an automatic signature machine utilized a series of documents which were connected edge to edge and which included perforated sides. These perforated sides engaged mating pin feed tractors located adjacent the pantograph system so that each document of the connected series could be accurately positioned beneath the pantograph. However, the documents produced by such an automatic signature machine contained a tear mark where the documents were separated and the performated strips removed so that these documents had the distinct appearance of the being mass produced which was undesirable. In addition, the recent widespread adaption of single feed work processors has resulted in the virtual abandonment in many applications of connected sheets.
Therefore, there existed in the prior art a need for a sheet transport mechanism to automatically position a single sheet from a stack of similar sheets beneath a pantograph system.